I always say that I have a love/hate relationship with my Dexcom but, for me, the pros defintely outweigh the cons and I would never give it up willingly.
The technology is not perfect - you will read on other threads of inaccurate readings and I have seen those but not often enough to be a problem for me. I've found that when I have inaccuracies it's when I'm rising or dropping very fast and the Dex seems to get confused and not know when to stop.
Remember too that the Dexcom isn't measuring directly from blood but rather it's measuring from subcutaneous fluid, meaning it's about 15 to 20 minutes behind your blood glucose reading. Thus, it's not a substitute for testing with a meter. If the Dex tells me I'm low, I'm probably already lower than what it's telling me.
It took me a month or two to learn how to use the Dex. Never take insulin or treat a low based only on the Dex...always verify with fingerstick. Otherwise, you risk riding a roller coaster. Learned that one the hard way.
The most beneficial thing for me is ability to see the trend lines and alarms for rapid rise or fall. When I get an alarm or see a trend I'm not expecting, that's my cue to test more often and keep a closer eye on it.
If I see that I'm trending down, I can verify then bump it up or stop the fall if I choose by eating something before I'm actually low. If I'm rising, I can correct before I get sky high.
Some people think the inaccuracies of the Dex are more trouble than it's worth for them. We all have to decide for ourselves what tools we want in our toolkit. For me, as someone who is hypo unaware, the Dexcom has been a lifesaver many times over and gives me peace of mind.